Semiconductor devices based on silicon, such as transistors and photodiodes, have been widely used for the past three decades. In recent years, semiconductor devices based on alternative materials, such as germanium, are becoming more widely used because they can offer advantages over silicon-based semiconductor devices. For example, pure germanium (Ge) as well as its silicon alloys (hereinafter “SiGe”), which exhibit a molar ratio of silicon to germanium according to Si1-xGex, may be advantageous in the area of photodetectors, because their bandgaps are more adjustable than those of silicon-only materials. This allows SiGe devices to more efficiently capture photons and makes SiGe devices attractive in the area of photodetectors.